<div>
  {{questionString}}
  <div class="row-fluid">
    <div class="span7">
      <textarea ng-model="proofString" ng-trim="false" rows="10" cols="50"></textarea>
      <button ng-click="submitProof()">Submit</button>
    </div>
    <div class="span5" ng-show="proofError">
      <pre>{{proofError}}</pre>
    </div>
  </div>
</div>

